Measurements have been made of ion energies in an electron cyclotron resonance plasma, under conditions typically employed for semiconductor materials processing. Both ion energies along magnetic field lines and ion energy distributions generated by a radio frequency (rf) sheath are characterized. Ion impact energies are found to vary between 10 and 35 eV under the conditions studied, with corresponding distribution widths from 3 to 8 eV. Ion energy distributions through an rf sheath are found to be highly dependent on bias frequency, with narrower distributions occurring at higher frequencies. Consequences of measured ion energies for processing results are discussed.

An electron cyclotron resonance plasma reactor has been built in order to study the filling of high aspect-ratio features on semiconductor devices with metal. The reactor produces a plasma of copper which is nearly 100% ionized at the substrate, without the use of any buffer or carrier gas. The ion flux is dependent on both the feed rate of copper neutrals into the plasma region, and on the microwave power absorbed in the plasma. Solid filling of features having aspect ratios as high as 4.2 is demonstrated, and a simple model is derived to explain the fill characteristics.

Photoresist removal was studied using single-crystal silicon samples mounted on a ceramic heater in an UHV compatible chamber. The photoresist-coated sample was exposed to an ozone-oxygen mixture at atmospheric pressure and at a flow rate of 4 s ℓ/min. Resist removal rate was measured using in situ laser interferometry. The removal rate was found to be a linear function of ozone concentration with a slope of 0.82 nm/s/unit mass fraction at a substrate temperature of 200 °C. The linearity is consistent with a simple chemical rate model. Typical photoresist removal rates at a mass density fraction ozone concentration of 0.09 ranged from 2.5 to 13 nm/s for substrate temperatures ranging from 150 to 300 °C, respectively. These rates are comparable with those observed by others. Over this temperature range, removal rates follow standard Arrhenius behavior from which an activation energy of 5.2 kcal/mol was determined. This value is similar to the known activation energy of 6.0 kcal/mol for the thermal dissociation of ozone leading us to conclude that thermal dissociation is the rate limiting step in the process. Our result is also significantly lower than reported previously and may be more accurate since the substantial shrinkage of photoresist with temperature was accounted for in these results. Additionally, the combination of concentration and temperature information is shown to lead to an effective chemical reaction rate constant for the removal of photoresist with ozone.

Sources of particles in a ciosedcoupled electron cyclotron resonance plasma source used for polysiiicon etch included flaking of a residual film deposited on chamber surfaces and shedding of material from the electrostatic wafer chuck. A large. episodic increase in the number of particles added to a wafer in a clean system is ObSeNed more frequently for a plasma-on than for a gas-only source condition. For film-forming process conditions, particles were added to wafers by a residual film, which was observed to fracture and flake away from chamber surfaces. The presence of a plasma, especially when radiofrequency bias is applied to the wafer, caused more particles to be ejected from the walls and added to wafers than the microwave powers. A study of the effect of electrode temperatures on particles added showed that thermophoretic and gravitational forces are not significant for this electron cyclotron resonance operating configuration. Particles originating from the electrostatic chuck were observed to be deposited on wafers in much larger numbers in the presence of the plasma as compared with gas-only conditions, implying the existence of a large ion drag force.

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